The overall long-term objective of this research program is to understand the development of internal models or representations that underlie sensorimotor behavior. Previous research suggests that so-called sensorimotor internal models, or maps, are the basis for the control of target-directed movements. These maps can be conceptualized as computational transformations of eye- (for vision) or head-centered (for audition) coordinate frames to neural commands controlling the effector e.g. in hand-centered coordinates. To date, studies about the development of sensorimotor maps, and their interactions are lacking. Specific aim 1 is to determine the characteristics of the development of either kinesthetic-motor or auditory-motor internal representations (intramodal condition). Specific aim 2 is to determine the development of either kinesthetic-visuo-motor or auditory-visuo-motor internal representations (intermodal condition) in 5 to 10 year old children. A neural basis for interactions of internal models of different modalities is suggested in the posterior parietal cortex, where neurons have been shown to code both visual and auditory signals and map them onto hand-centered coordinates. These experiments will allow determination of the characteristics of intra- and intermodal motor map differentiation, and to obtain a developmental landscape of these characteristics. The PIs hypothesize that (1) intramodal motor representations are very broadly tuned in young children, resulting in considerable performance variability; (2) with increasing age, these internal representations become better 'tuned'; and (3) in intermodal contexts the less well-defined (intramodal) sensorimotor representations are more susceptible to being affected by better defined internal models. This is supported by preliminary results showing stronger auditory-motor aftereffects after a visuo-motor adaptation condition in young children than in older children, who are likely to have better-tuned intramodal sensorimotor models. The overall significance of the work proposed lies in addressing two knowledge gaps that stand in the way of having better insights into how sensorimotor representations develop and interact in children. Understanding this is an essential foundation for future work on developmental motor impairments such as developmental coordination disorder (DCD). [unreadable] [unreadable] [unreadable] [unreadable]